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MDAC first listen (part V)

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FWIW, after a few weeks back with the CDQ, I went back to the MDAC today and it is indeed a better sounding device. This time I've added in the sub and I've been enjoying some great tunes. I'll probably stick with MDAC plus one of those cheap Behringer UCA222s (to convert phono stage output to digital optical) until the CDQ+ upgrade is available, then perhaps sell the MDAC (my wife wants to stick with Nait2+AVIs in 'her' system aka the second system, due to familiarity with that system and suspicion of strange black boxes...)
 
Is it really good enough to replace something like a Classé DR-6 mkII as pre? Also, how are you incorporating your TT into such a setup?



Lefty

I'm currently beset on all sides by pre-amps. I have Krell KSP-7B, one of Guys excellent Puresound L10's and a lightly breathed on XTC-pre-1. The Mdac is currently on loan with Flat-p. I think I'll end up with the Goldpoint twin input stepped volume unit. It has two inputs one of which can be set to bypass- which I'll use for the dac, and the other one I'll to control the level of my Su-Prefix.
 
Ok, my knowledge with regards to electronics is rather limited (understatement). Here's a stupid question, how does the output current relate to output power?

Power is directly related to current and voltage (P=I*V) and will vary according to the load from the headphone (Impedance) to keep things simple ;)
Low impedance headphone usually require more current while high impedance ones prefer high voltage.
Many dedicated headphone amp such as Violectric V200 are able to deliver around 200/250mA in a 50 Ohms load, others even more.
But most headphones today have high sensitivity so more power doesn't always result in better sound.
 
Last Saturday we had a "get together" with a few audio enthusiasts. As several people had different DAC's we thought it would be interesting to organize a comparison. Three members brought their DAC's for a listening test. There was the W4S Dac2, a Bresford Caiman TC-7520SE and the MDAC. We tested all DAC's with a Marantz CD player who was connected by means of coax spdif to the DAC under test. The Bresford was the first that had to give in. It was absolutely no match for the other two DAC's in the line up. The sound of the Bresford was more "closed" and had a lot less definition. The sound was less pronounced in the bass as well. The MDAC and the W4S are very close to eachother and it turned out to be very difficult to find differences. The only difference we could find is that the MDAC has a bit more depth in the bass. I can only conclude that the MDAC is a terrific performer and it is only half the price of the W4S.
 
Power is directly related to current and voltage (P=I*V) and will vary according to the load from the headphone (Impedance) to keep things simple ;)
Low impedance headphone usually require more current while high impedance ones prefer high voltage.
Many dedicated headphone amp such as Violectric V200 are able to deliver around 200/250mA in a 50 Ohms load, others even more.
But most headphones today have high sensitivity so more power doesn't always result in better sound.

Ok, I got it. Now that you've typed that I actually recall quite a bit of it.

I guess where I'm a bit fuzzy/confused is when John states "Output current limited to +/- 120mA (Before current limit starts to kickin)", is that the same as when HeadAmp lists the GS-1's output power as 1W or CEntrance lists the DACmini's headphone output power as 1.5W(total)?

Sorry for being a bit thick, I'm just trying to get a sense of how the specs in the headphone amp of the M-DAC stacks up in comparison to others I've owned. I've been quite happy with it's performance with the LCD-2's but I've also read quite a bit that states a general rule of thumb is they work best with amps that have output power more in the 1 - 2W range and most of the HiFiMan's seem to like even more, especially the HE-6.
 
Ok, I got it. Now that you've typed that I actually recall quite a bit of it.

I guess where I'm a bit fuzzy/confused is when John states "Output current limited to +/- 120mA (Before current limit starts to kickin)", is that the same as when HeadAmp lists the GS-1's output power as 1W or CEntrance lists the DACmini's headphone output power as 1.5W(total)?

Sorry for being a bit thick, I'm just trying to get a sense of how the specs in the headphone amp of the M-DAC stacks up in comparison to others I've owned. I've been quite happy with it's performance with the LCD-2's but I've also read quite a bit that states a general rule of thumb is they work best with amps that have output power more in the 1 - 2W range and most of the HiFiMan's seem to like even more, especially the HE-6.

The MDAC has a unique output stage design "CROSS" that provides an inherently low output impedance (it does not rely on overall globe feedback to reduce output stage impedance and distortion) - this makes the CROSS output stage ideal to drive "difficult" loads such as headphones.

The CROSS output stage topology gives you finesse and control over brute force...
 
Without knowing the output voltage or load there is little we can deduce from the 120mA, just that it is on the low scale compared to many dedicated headphone amps. John might want to chime in to reveal more about power output for different load.
The GS1 appears to have only slightly more current output than the M-DAC but my guess is that output voltage should be better.
 
Ok, I got it. Now that you've typed that I actually recall quite a bit of it.

I guess where I'm a bit fuzzy/confused is when John states "Output current limited to +/- 120mA (Before current limit starts to kickin)", is that the same as when HeadAmp lists the GS-1's output power as 1W or CEntrance lists the DACmini's headphone output power as 1.5W(total)?

Sorry for being a bit thick, I'm just trying to get a sense of how the specs in the headphone amp of the M-DAC stacks up in comparison to others I've owned. I've been quite happy with it's performance with the LCD-2's but I've also read quite a bit that states a general rule of thumb is they work best with amps that have output power more in the 1 - 2W range and most of the HiFiMan's seem to like even more, especially the HE-6.

My general impression is that there is an arms race going on in the headphone amp world. @Seranil mentioned an LD amp capable of a nominal 70Vp-p swing into 120ohms, which equates to a current draw of 583mA and 40.83W of power. That is a HUGE amount of power. It's difficult to conceive of a headphone transducer requiring that much.
 
Little Dot is reported to ONLY output 5W into 120 Ohm and was specifically designed to power the AKG K1000 (Sensitivity: 74dB for 1mW). It is also great with the very difficult to drive Hifiman HE-6 ( sensitivity of 83.5dB)
 
Hi John, I've got my M-Dac plugged into my 2 year old Sony Vaio and I'm using Foobar and Wasapi. I've followed the manual and changed all the settings as suggested. The buffer is set to 50ms. I still get drop outs every 40s or so just as PhilC posted many months ago. I've changed the laptop power output as you suggested to him, but I still get probs. It's a decent spec machine so I don't get why it is failing. I normally use Sonos and that has worked perfectly, I'm only using the laptop as I'm getting married in a couple of months so I need a portable non networked solution. I'm in the process of copying the music off the NAS to the local hardrive on the laptop, but I'm not confident of an improvement as the Sonos accesses it from there with no trouble. I do also own an rdac so I could see if the drop outs occur on that if it helps. By the way I changed the display to show the buffer level, it tends to wobble around 50%, then I hear a pop, and see the buffer drop to around 20%. Thanks, James

I gave up with WASAPI and windows 7 32bit stick with Asio4All, double check the manual to make sure everything is set correctly. Manual is spot on.

Not sure if its coincidence as I've just added Tacima filter block ,
but as yet have not had an issue for a while with an inactive usb.

Been busy so have not had prolonged listening to give a good work out. Halfterm kids on ps3 all the time and new baby etc. etc...

Might be time for a set of decent headphones.
 
Sorry, I stand corrected. I should not have taken peak-to-peak value into ohms law, I believe RMS is the relevant figure here:

70Vp-p / 2.8 = 25V RMS. 25V into 120 ohms draws ~200mA = 5W.

Sanity restored. Still, while the K-1000 and HE-6 undoubtedly require some heft, they are clearly the extreme outliers in the distribution of headphone power input requirements. People are known to plug these directly into speaker taps.
 
Hi,
I run my HE-500s direct from the XLR outputs on the MDAC, using an adaptor cable of 2 x 3 pin XLR to 4 pin XLR socket, which then connects to a balanced cable from the HE-500s terminated in a 4 pin XLR plug. This allows me to run balanced throughout, and also use the phones with a Little Dot MkVI - although that is becoming rarer now, as the MDAC sounds so good used directly :)

Hope this might help someone - it's another way of doing it without shelling out for a separate headphone amp.
Cheers,
George
 
I'm very close to purchasing an MDAC, and I've read through so many threads and posts tonight my brain is about to explode! Could you please confirm a few things which I read on earlier posts and now seem to have now changed?
- will there definitely be some kind of psu modifications, be it on the boards, or to the external psu, or both? Or will any third party be doing this on a custom basis, if Lakewest aren't going to (or even anyone planning a DIY PSU module)?
- is there definitely a transport/streamer, clock locked to the MDAC in the works?
- did anything ever become of the plan to attempt clock-locking a Squeezebox Touch?
Many thanks!
James
 
- is there definitely a transport/streamer, clock locked to the MDAC in the works?
- did anything ever become of the plan to attempt clock-locking a Squeezebox Touch?
Many thanks!
James
I'm using an SB Touch with the MDAC and it sounds absolutely wonderful. I don't know what you mean by clock locked but the MDAC works great with the SBT; the MDAC locks just fine. My SBT is connected with optical spdif. Works like a charm.
You won't regret purchasing the MDAC. it is a great DAC that can easily compete with very expensive models.
 
Hi,
I run my HE-500s direct from the XLR outputs on the MDAC, using an adaptor cable of 2 x 3 pin XLR to 4 pin XLR socket, which then connects to a balanced cable from the HE-500s terminated in a 4 pin XLR plug.

Interesting setup!

Did you make the cables up yourself, or did you buy them somewhere? Could be worth exploring when I get my MDAC.

Lefty
 
I'm currently beset on all sides by pre-amps. I have Krell KSP-7B, one of Guys excellent Puresound L10's and a lightly breathed on XTC-pre-1. The Mdac is currently on loan with Flat-p. I think I'll end up with the Goldpoint twin input stepped volume unit. It has two inputs one of which can be set to bypass- which I'll use for the dac, and the other one I'll to control the level of my Su-Prefix.

So does the MDAC perform better as a preamp than the others in the context of your system?

Is this the Goldpoint unit you mean?

http://www.goldpt.com/sa2.html

If so, is there a UK supplier for it? Looks interesting :)

Lefty
 
I'm using an SB Touch with the MDAC and it sounds absolutely wonderful. I don't know what you mean by clock locked but the MDAC works great with the SBT; the MDAC locks just fine. My SBT is connected with optical spdif. Works like a charm.
You won't regret purchasing the MDAC. it is a great DAC that can easily compete with very expensive models.

There were plans afoot at one point to offer a SBT upgrade to take advantage of the MDACs ability to clock-lock. Although its jitter attenuation is apparently good, this could presumably only benefit things. Likewise the PSU mods, or JohnW's own transport with clock lock, etc. they were much touted and I just wanted to know about potential upgrade paths in the current moment before buying, is all. Shame to have the clock out feature there and not use it.
 
Lefty, I actually use my Weiss 202 as my first choice source and so far no additional pre-amp has bested it. But I need a preamp to cOntrol the level on my phonostage and provide source switching, so the Goldpoint unit which provides bypass function and level control for the second source should be perfect. Yeh it's that unit, no uk source.
 
There were plans afoot at one point to offer a SBT upgrade to take advantage of the MDACs ability to clock-lock. Although its jitter attenuation is apparently good, this could presumably only benefit things. Likewise the PSU mods, or JohnW's own transport with clock lock, etc. they were much touted and I just wanted to know about potential upgrade paths in the current moment before buying, is all. Shame to have the clock out feature there and not use it.

There's also the option to connect the SBT to MDAC via async USB using Triode's work over on the slimdevices forums...that way the MDAC is the master clock in any case.
 
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